Yes, there will be pushback from industry and its legions of lobbyists. Obama will be hammered by opponents warning of massive job losses and threats to energy security.

But the voters spoke clearly in November. Americans gave Obama a mandate to continue his agenda. Opinion polls show his approval rating is more than three times that of Congress: Recent Gallup surveys show Obama’s approval rating at 51 percent and Congress eking out 14 percent.

President Obama made some ground-breaking strides in his first term. He enacted new car mileage standards that will cut carbon emissions from cars in half.

He boldly put a stake in the ground in his inaugural address. He knows what we know: the science isn’t a mystery, nor is the path to a solution. Carbon dioxide emissions are the greatest contributors to climate change, and not coincidentally are also major causes of health-damaging air pollution. And coal-fired power plants account for nearly 30 percent of America's carbon pollution.

The administration already is preparing to tighten regulations on new coal plants. But more important, it also should mandate the modernization of existing power plants, many of which are aging cash cows for the big coal burners. Those plants should be retrofitted with new clean technology or converted to natural gas. That would slash their carbon emissions in half.

Next, the Obama administration should halt construction of the Keystone XL pipeline which will turn on the spigots for oil from Canada’s tar sands, one of the dirtiest and most environmentally damaging fossil fuel sources on the planet.

The Canadian pipeline company has agreed—under pressure—to reroute the planned path away from aquifers and drinking water supplies in Nebraska. But that represents only a fraction of the overall environmental threat.

The oil taken from Canada’s tar sands will unleash 20 times the carbon pollution of conventional drilling. If we're trying to reduce carbon pollution, promoting the massive use of tar sands oil is like saying you want to eat healthier and going to McDonald's for every meal.

Obama’s third immediate option for action is refusing to expand oil and gas exploration in Alaska’s Arctic seas where an estimated 1.5 million birds nest and raise their young. There are cheaper, more plentiful sources.

Shell Oil's attempts at Arctic exploration in recent months adds up to a flashing red light.

Shell’s custom-built oil spill containment dome was crushed during a calm-water test; its drill rigs have been washed ashore twice, its oil response barge does not meet Coast Guard standards; and the company was forced to abandon its first exploratory drill after just a few hours when an ice sheet 10 times the size of Manhattan began roaring toward the site. Shell also has reneged on claims of how effectively it could react to an oil spill.

Scientists concede that so little is known about how to clean up an oil spill or other disaster in these frigid waters that the Deep Water Horizon spill in the Gulf would look like a picnic in comparison to a similar event in the Arctic seas.

The Obama administration now is considering proposals to expand the number of companies allowed to drill in the Arctic seas. President Obama should reject those requests unequivocally and order a ban on all oil exploration and drilling in the two key Arctic seas.

President Obama has the chance to not only change the course of history in the next four years; he can change the course of the lives of Americans for generations to come. And, after all, he promised.

Yarnold is president and CEO of National Audubon Society.